That's OK for the first two (unless you're cruising somewhere warm). But health experts now say you shouldn't pack away the sunscreen.

"Some people may think that protecting the skin from the sun in the winter is not as important because they are not feeling the heat as much in the winter," said Dr. April Armstrong, a Sacramento, Calif., dermatologist and assistant professor at the University of California, Davis, School of Medicine. "Oftentimes, some people get a false sense of security from the cold temperature and conclude that they are not experiencing the harmful effect of UV [ultraviolet] rays. As a result, some people may not be as diligent putting on sunscreen during the winter."

In fact, some might not apply it at all, said Dr. Arielle Kauvar, clinical associate professor of dermatology at New York University School of Medicine and a spokeswoman for the Skin Cancer Foundation.

"People should be wearing sunscreen all year-round," she said. But she suspects that no more than 20% of the population do so.

It's true that ultraviolet B rays -- those responsible for sunburns and skin cancer -- are not as intense during the winter months, Kauvar said. But UVA rays remain constant, contributing to skin cancer as well as skin aging, she said.

"Winter sports can be hard on the skin," Armstrong said. "Winter sports such as skiing, snowboarding and snowshoeing often leave a person exposed in the sun for long periods of time."

Exposed skin -- even if that's only on the face -- takes in UV rays from above and below: rays from the sun and the reflection off the snow.

"Often, winter sports are associated with higher elevations and reflection of ultraviolet light off the snow," said Dr. Elizabeth Tanzi, an assistant professor of dermatology at Johns Hopkins Hospital in Baltimore and a dermatologist in Washington, D.C.

Think like you would at the beach, she said, even if the temperature is below zero. Use sunscreen of at least an SPF (sun protection factor) of 30, and reapply it every two or three hours.

And wearing sunglasses can not only help prevent cataracts, Kauvar said, but also help prevent skin cancers around the eyelids. Such cancers, she said, are not uncommon.

Rules for sunscreen use in the winter are pretty similar to those for summer, Armstrong said. Wear sunscreen daily, reapply often and opt for cream-based products over lotions because they're thicker. Extra applications might be needed if you're skiing intensely and sweating.

And be sure the selected sunscreens offer protection from both UVA and UVB rays. Kauvar said she tells people to look for physical-blocker sunscreens, which have zinc oxide. Physical blockers reflect or scatter the UV rays rather than absorbing them.

For people who aren't participating in outdoor sports, Kauvar said, it's probably reasonable to wear a moisturizer with sunscreen. But be sure the SPF is at least 30, she said.